Kinetic studies on the temperature dependence of the BrO + BrO reaction using laser flash photolysis

The BrO self-reaction, BrO + BrO → products (1), has been studied using laser flash photolysis coupled with UV absorption spectroscopy over the temperature range T = 266.5-321.6 K, under atmospheric pressure. BrO radicals were generated via laser photolysis of Br(2) in the presence of excess ozone. Both BrO and O(3) were monitored via UV absorption spectroscopy using charge-coupled device (CCD) detection. Simultaneous fitting to both temporal concentration traces allowed determination of the rate constant of the two channels of , BrO + BrO → 2Br + O(2) (1a); BrO + BrO → Br(2) + O(2) (1b), hence the calculation of the overall rate of and the branching ratio, α: k(1a)/cm(3) molecule(-1) s(-1) = (1.92 ± 1.54) × 10(-12) exp[(126 ± 214)/T], k(1b)/cm(3) molecule(-1) s(-1) = (3.4 ± 0.8) × 10(-13) exp[(181 ± 70)/T], k(1)/cm(3) molecule(-1) s(-1) = (2.3 ± 1.5) × 10(-12) exp(134 ± 185 /T) and α = k(1a)/k(1) = (0.84 ± 0.09) exp[(-7 ± 32)/T]. Errors are 1σ, statistical only. Results from this work show a weaker temperature dependence of the branching ratio for channel (1a) than that found in previous work, leading to values of α at temperatures typical of the Polar Boundary Layer higher than those reported by previous studies. This implies a shift of the partitioning between the two channels of the BrO self-reaction towards the bromine atom and hence directly ozone-depleting channel (1a).     

Five non‐synonymous SNPs in the gene encoding human deoxyribonuclease I‐like 2 implicated in terminal differentiation of keratinocytes reduce or abolish its activity

Several non‐synonymous SNPs in the human deoxyribonuclease I‐like 2 (DNase 1L2) gene responsible for DNA degradation during terminal differentiation of epidermal keratinocytes have been identified. However, only limited population data are available, and furthermore the effect of these SNPs on the DNase 1L2 activity remains unknown. Genotyping of all of the 17 SNPs was performed using the PCR‐RFLP method in three ethnic groups including 14 different populations. A series of amino acid‐substituted DNase 1L2 corresponding to each SNP was expressed, and its activity was measured. All of the six non‐synonymous SNPs exhibited a mono‐allelic distribution, whereas the distribution of some SNPs other than exonic ones was ethnicity‐dependent. Each of the minor alleles in SNPs, p.Ala20Asp, p.Val104Leu, p.Asp197Ala, p.Glu274Lys and p.Asp287Asn, among the non‐synonymous SNPs produced low or no activity‐harbouring DNase 1L2. DNase 1L2 is well conserved, retaining full levels of enzymatic activity, with regard to these exonic SNPs in human populations. It seems plausible to assume that these SNPs affecting the activity may be one of the factors responsible for a genetic pre‐disposition for failure of differentiation‐associated cell death in various keratinocyte lineages, thereby leading to the development of parakeratosis. Our results may have clinical implications in relation to the pathogenesis of parakeratosis.     

A Combined 6π-Azaelectrocyclization/Staudinger Approach to Protein and Cell Engineering: Noninvasive Tumor Targeting by N-Glycan-Engineered Lymphocytes

A Combined 6π-Azaelectrocyclization/Staudinger Approach to Protein and Cell Engineering: Noninvasive Tumor Targeting by N-Glycan-Engineered Lymphocytes

All authors

Katsunori Tanaka, Kaori Minami, Tsuyoshi Tahara, Eric R. O. Siwu, Koichi Koyama, Satoshi Nozaki, Hirotaka Onoe, Yasuyoshi Watanabe & Koichi Fukase

https://doi.org/10.1080/07328303.2010.483042

Published online:

02 June 2010

Graphical Abstract     

584.

Photochemical synthesis and electronic spectra of fulminene ([6]phenacene)     

Hideki Okamoto  Minoru Yamaji  Shin Gohda  Kaori Sato  Hisako Sugino  Kyosuke Satake 《Research on Chemical Intermediates》2013,39(1):147-159

Facile synthesis of fulminene ([6]phenacene) was achieved through the Mallory reaction of 1-(1-naphthyl)-2-(1-phenanthryl)ethene or the 9-fluorenone-sensitized photo-ring-closure of 1-(1-naphthyl)-2-(1-phenanthryl)ethane. The electronic spectral properties of fulminene were investigated for the first time using photoluminescence as well as transient absorption spectroscopy. The spectral features were compared with those of a series of lower phenacene homologs such as phenanthrene ([3]phenacene), chrysene ([4]phenacene), and picene ([5]phenacene). For the [n]phenacene series, both the fluorescence and phosphorescence bands linearly red-shifted with an increase in the number of the benzene rings (n). Trends in the energy levels of the excited singlet (E _S) and the triplet (E _T) states were expressed as E _s = ?2.6n + 89.1 (kcal mol^?1) and E _T = ?1.8n + 66.2 (kcal mol^?1), respectively. In the case of fulminene, laser flash photolysis displayed a transient spectrum with an absorption maximum (λ _max ^T–T ) at 675 nm, which was assigned as the triplet fulminene excited state. The λ _max ^T–T values for the [n]phenacene series showed a linear correlation as a function of the ring number n, given by an equation, λ _max ^T–T  = 60n + 318 (nm).     

585.

A theoretical study on the origin of pi-facial stereoselectivity in the alkylation of enolates derived from 4-substituted gamma-butyrolactones     

Ando K 《Journal of the American Chemical Society》2005,127(11):3964-3972

The alkylation of 4-methoxymethyl-gamma-butyrolactone enolate with methyl chloride was studied at the B3LYP/6-31+G* level. Conformer search of the free enolate gave 15 unique conformers within 5.39 kcal/mol. The transition structures for both anti- and syn-attacks of methyl chloride on these 15 conformers were located. In all cases, the anti-transition structures are more stable than the corresponding syn-ones. The alkylation of gamma-valerolactone was studied at the MP2, B3LYP, and HF levels of theory with the 6-31+G* basis set in the presence of Li+ and dimethyl ether molecules. Basis set effects were also examined by the comparison of the MP2 results with the 6-31+G*, 6-31+G**, and 6-311+G** basis sets in one case. This study shows that the main source of the anti-selectivity of 4-substituted gamma-butyrolactones is eclipsing strain in the syn-transition structures.     

586.

Effect of chlorosilanes on the radical polymerization of styrene and methyl methacrylate     

Yuji Minoura  Yasushi Enomoto 《Journal of polymer science. Part A, Polymer chemistry》1968,6(1):13-20

Styrene (St) and methyl methacrylate (MMA) were polymerized by azobisisobutyronitrile at 50°C. in the presence of silanes such as tetramethylsilane, trimethylcholorosilane, dimethyldichlorosilane, methyltrichlorosilane, and tetrachlorosilane. The polymerization rates of both St and MMA in the presence of silanes were nearly equal to those in the absence of silanes. On the other hand, the molecular weights decreased gradually as the concentration of chlorosilane increased. The chain transfer constants of all the silanes in the polymerization of St and MMA at 50°C. were calculated by Mayo's equation. The chain transfer constants of Me₄Si, Me₃SiCl, Me₂SiCl, MeSiCl₃, and SiCl₄ were 0.31 × 10^?3, 1.25 × 10^?3, 1.78 × 10^?3, 1.92 × 10^?3, and 2.0 × 10^?3, for St and 0.13 × 10^?3, 0.22 × 10^?3, 0.245 × 10^?3, 0.27 × 10^?3, and 0.30 × 10^?3, for MMA, respectively. From these results, it was found that the Si? Cl bond was radically cleaved. The Q_tr values of the silanes, in the same order as above, were found to be 1.03 × 10^?4, 2.33 × 10^?4, 2.83 × 10^?4, 3.10 × 10^?4, and 3.35 × 10^?4, respectively and the e_tr values were +0.58, +1.30, +1.50, +1.48, and +1.43, respectively.     

587.

Fabrication of vertically aligned liquid crystal cell without using a conventional alignment layer     

Masanobu Mizusaki  Yohei Nakanishi  Satoshi Enomoto 《Liquid crystals》2018,45(2):270-278

We propose a novel method to fabricate a vertical alignment (VA) of liquid crystal (LC) molecules without using a conventional alignment layer such as polyimide film. The method produces the vertical alignment polymer layer (VAPL) by polymerisation of a monomer or mixed monomers including in the LC layer above T_NI of the LC material. The VA mode LC cell with the VAPL (VAPL-LC cell) produced from the mixed monomers of acrylic acid 4-(4?-octyloxy-biphenyl-4-yloxy)-butyl ester and 1,2-bis-(4-methacryloxy-phenyl)-2,2-dimethoxy-ethane-1-one exhibited enough level of alignment state and electro-optical property with high voltage holding ratio. We can expect that the VAPL-LC cell is useful for next-generation displays such as flexible liquid crystal displays because the method does not need the process including high temperature over 200°C.     

588.

Chemical synthesis of RNA via 2′-O-cyanoethylated intermediates     

Hisao Saneyoshi  Kaori Ando  Mitsuo Sekine 《Tetrahedron》2007,63(45):11195-11203

It was found that 2′-O-cyanoethyl group could be removed from 2′-O-cyanoethylated ribonucleoside derivatives by treatment with Bu₄NF. This finding was successfully applied to the synthesis of oligoribonucleotides via their 2′-O-cyanoethylated derivatives as key intermediates where a cyanoethyl group was used as the 2′-hydroxyl protecting group. The rate of condensation using this protecting group in the presence of various activators was generally faster than that observed when a TBDMS group was used as the protecting group.     

589.

Metal-ion-dependent GFP emission in vivo by combining a circularly permutated green fluorescent protein with an engineered metal-ion-binding coiled-coil     

Mizuno T  Murao K  Tanabe Y  Oda M  Tanaka T 《Journal of the American Chemical Society》2007,129(37):11378-11383

Coordination of metal ions significantly contributes to protein structures and functions. Here we constructed a fusion protein, consisting of a de novo designed, metal-ion-binding, trimeric coiled-coil and a circularly permutated green fluorescent protein (cpGFP), where the fluorescent emission from cpGFP was induced by metal ion coordination to the coiled-coil. A circularly permutated GFP, (191)cpGFP(190), was constructed by connecting the original N- and C-termini of GFP(UV) by a GGSGG linker and cleaving it between Asp(190) and Gly(191). The metal-ion-binding coiled-coil, IZ-HH, was designed to have three alpha-helical structures, with 12 His residues in the hydrophobic core of the coiled-coil structure. IZ-HH exhibited an unfolded structure, whereas it formed the trimeric coiled-coil structure in the presence of divalent metal ions, such as Cu(2+), Ni(2+), or Zn(2+). The fusion protein (191)cpGFP(190)-IZ-HH was constructed, in which (191)cpGFP(190) was inserted between the second and third alpha-helices of IZ-HH. Escherichia coli cells, expressing (191)cpGFP(190)-IZ-HH, exhibited strong fluorescence when the Cu(2+) and Zn(2+) ions were present in the medium, indicating that they passed through the cell membrane and induced the proper folding of the (191)cpGFP(190) domain. This strategy, in which protein function is regulated by a metal-ion-responsive coiled-coil, should be applicable to the design of various metal-ion-responsive, nonnatural proteins that work both in vitro and in vivo.     

590.

Mononuclear and dinuclear monoperoxovanadium(v) complexes with a hetero ligand. 1.(1) Self-decomposition reaction, detection of reactive oxygen species, and oxidizing ability     

Kanamori K  Nishida K  Miyata N  Shimoyama T  Hata K  Mihara C  Okamoto K  Abe Y  Hayakawa S  Matsugo S 《Inorganic chemistry》2004,43(22):7127-7140

A mononuclear peroxovanadium(V) complex with histamine-N,N-diacetate (histada), K[VO(O(2))(histada)], and a dinuclear peroxovanadium(V) complex with 2-oxo-1,3-diaminopropane-N,N,N',N'-tetraacetate (dpot), Cs(3)[(VO)(2)(O(2))(2)(dpot)], were prepared and characterized. The self-decomposition reaction was examined for these peroxovanadium(V) complexes as well as for K[VO(O(2))(cmhist)] (cmhist = N-carboxymethylhistidinate). The reaction profiles depicted by the absorbance change in the UV-vis spectrum show a sigmoid shape with an induction period. The induction period is reduced by the addition of acid, fluoride, thiocyanate, VO(2+), VO(2)(+), and trolox compared to the solution containing perchlorate. On the other hand, the induction period was elongated by the addition of chloride, bromide, and 2-tert-butyl-p-cresol. These behaviors are discussed on the basis of a radical chain mechanism. The self-decomposition reactions have also been followed by the (1)H and (51)V NMR and EPR spectra. These spectral studies as well as the UV-vis spectral study indicate that vanadium(V) is partly reduced to vanadium(IV) in the self-decomposition process. The histada complex yields a mixed-valence dinuclear complex in a concentrated solution, and the dpot complex yields a mixed-valence tetranuclear complex. The reduction of vanadium ion suggests that the peroxo ligand may act as a reducing agent. In order to know the fate of the peroxo ligand, we tried to detect superoxide anion and hydroxyl radical, which were anticipated to be produced in the self-decomposition process. The formation of superoxide anion was spectrophotometrically confirmed using two independent methods, including the reduction of cytochrome c and the reduction of sodium 4-[3-(iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate (WST-1). The formation of hydroxyl radical was confirmed by an EPR spin trapping technique. The oxidizing abilities of the peroxovanadium(V) complexes toward bovine serum albumin (BSA) were also evaluated. In the protein carbonyl assay, it was found that the total amount of protein carbonyl in BSA was increased by the reaction with the peroxovanadium complexes in the concentration-dependent manner. In addition, the oxidation of sulfhydryl group in BSA induced by the peroxovanadium complexes was confirmed.     

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Photochemical synthesis and electronic spectra of fulminene ([6]phenacene)

Facile synthesis of fulminene ([6]phenacene) was achieved through the Mallory reaction of 1-(1-naphthyl)-2-(1-phenanthryl)ethene or the 9-fluorenone-sensitized photo-ring-closure of 1-(1-naphthyl)-2-(1-phenanthryl)ethane. The electronic spectral properties of fulminene were investigated for the first time using photoluminescence as well as transient absorption spectroscopy. The spectral features were compared with those of a series of lower phenacene homologs such as phenanthrene ([3]phenacene), chrysene ([4]phenacene), and picene ([5]phenacene). For the [n]phenacene series, both the fluorescence and phosphorescence bands linearly red-shifted with an increase in the number of the benzene rings (n). Trends in the energy levels of the excited singlet (E _S) and the triplet (E _T) states were expressed as E _s = ?2.6n + 89.1 (kcal mol^?1) and E _T = ?1.8n + 66.2 (kcal mol^?1), respectively. In the case of fulminene, laser flash photolysis displayed a transient spectrum with an absorption maximum (λ _max ^T–T ) at 675 nm, which was assigned as the triplet fulminene excited state. The λ _max ^T–T values for the [n]phenacene series showed a linear correlation as a function of the ring number n, given by an equation, λ _max ^T–T  = 60n + 318 (nm).     

A theoretical study on the origin of pi-facial stereoselectivity in the alkylation of enolates derived from 4-substituted gamma-butyrolactones

The alkylation of 4-methoxymethyl-gamma-butyrolactone enolate with methyl chloride was studied at the B3LYP/6-31+G* level. Conformer search of the free enolate gave 15 unique conformers within 5.39 kcal/mol. The transition structures for both anti- and syn-attacks of methyl chloride on these 15 conformers were located. In all cases, the anti-transition structures are more stable than the corresponding syn-ones. The alkylation of gamma-valerolactone was studied at the MP2, B3LYP, and HF levels of theory with the 6-31+G* basis set in the presence of Li+ and dimethyl ether molecules. Basis set effects were also examined by the comparison of the MP2 results with the 6-31+G*, 6-31+G**, and 6-311+G** basis sets in one case. This study shows that the main source of the anti-selectivity of 4-substituted gamma-butyrolactones is eclipsing strain in the syn-transition structures.     

Effect of chlorosilanes on the radical polymerization of styrene and methyl methacrylate

Styrene (St) and methyl methacrylate (MMA) were polymerized by azobisisobutyronitrile at 50°C. in the presence of silanes such as tetramethylsilane, trimethylcholorosilane, dimethyldichlorosilane, methyltrichlorosilane, and tetrachlorosilane. The polymerization rates of both St and MMA in the presence of silanes were nearly equal to those in the absence of silanes. On the other hand, the molecular weights decreased gradually as the concentration of chlorosilane increased. The chain transfer constants of all the silanes in the polymerization of St and MMA at 50°C. were calculated by Mayo's equation. The chain transfer constants of Me₄Si, Me₃SiCl, Me₂SiCl, MeSiCl₃, and SiCl₄ were 0.31 × 10^?3, 1.25 × 10^?3, 1.78 × 10^?3, 1.92 × 10^?3, and 2.0 × 10^?3, for St and 0.13 × 10^?3, 0.22 × 10^?3, 0.245 × 10^?3, 0.27 × 10^?3, and 0.30 × 10^?3, for MMA, respectively. From these results, it was found that the Si? Cl bond was radically cleaved. The Q_tr values of the silanes, in the same order as above, were found to be 1.03 × 10^?4, 2.33 × 10^?4, 2.83 × 10^?4, 3.10 × 10^?4, and 3.35 × 10^?4, respectively and the e_tr values were +0.58, +1.30, +1.50, +1.48, and +1.43, respectively.     

Fabrication of vertically aligned liquid crystal cell without using a conventional alignment layer

We propose a novel method to fabricate a vertical alignment (VA) of liquid crystal (LC) molecules without using a conventional alignment layer such as polyimide film. The method produces the vertical alignment polymer layer (VAPL) by polymerisation of a monomer or mixed monomers including in the LC layer above T_NI of the LC material. The VA mode LC cell with the VAPL (VAPL-LC cell) produced from the mixed monomers of acrylic acid 4-(4?-octyloxy-biphenyl-4-yloxy)-butyl ester and 1,2-bis-(4-methacryloxy-phenyl)-2,2-dimethoxy-ethane-1-one exhibited enough level of alignment state and electro-optical property with high voltage holding ratio. We can expect that the VAPL-LC cell is useful for next-generation displays such as flexible liquid crystal displays because the method does not need the process including high temperature over 200°C.     

Chemical synthesis of RNA via 2′-O-cyanoethylated intermediates

It was found that 2′-O-cyanoethyl group could be removed from 2′-O-cyanoethylated ribonucleoside derivatives by treatment with Bu₄NF. This finding was successfully applied to the synthesis of oligoribonucleotides via their 2′-O-cyanoethylated derivatives as key intermediates where a cyanoethyl group was used as the 2′-hydroxyl protecting group. The rate of condensation using this protecting group in the presence of various activators was generally faster than that observed when a TBDMS group was used as the protecting group.     

Metal-ion-dependent GFP emission in vivo by combining a circularly permutated green fluorescent protein with an engineered metal-ion-binding coiled-coil

Coordination of metal ions significantly contributes to protein structures and functions. Here we constructed a fusion protein, consisting of a de novo designed, metal-ion-binding, trimeric coiled-coil and a circularly permutated green fluorescent protein (cpGFP), where the fluorescent emission from cpGFP was induced by metal ion coordination to the coiled-coil. A circularly permutated GFP, (191)cpGFP(190), was constructed by connecting the original N- and C-termini of GFP(UV) by a GGSGG linker and cleaving it between Asp(190) and Gly(191). The metal-ion-binding coiled-coil, IZ-HH, was designed to have three alpha-helical structures, with 12 His residues in the hydrophobic core of the coiled-coil structure. IZ-HH exhibited an unfolded structure, whereas it formed the trimeric coiled-coil structure in the presence of divalent metal ions, such as Cu(2+), Ni(2+), or Zn(2+). The fusion protein (191)cpGFP(190)-IZ-HH was constructed, in which (191)cpGFP(190) was inserted between the second and third alpha-helices of IZ-HH. Escherichia coli cells, expressing (191)cpGFP(190)-IZ-HH, exhibited strong fluorescence when the Cu(2+) and Zn(2+) ions were present in the medium, indicating that they passed through the cell membrane and induced the proper folding of the (191)cpGFP(190) domain. This strategy, in which protein function is regulated by a metal-ion-responsive coiled-coil, should be applicable to the design of various metal-ion-responsive, nonnatural proteins that work both in vitro and in vivo.     

Mononuclear and dinuclear monoperoxovanadium(v) complexes with a hetero ligand. 1.(1) Self-decomposition reaction, detection of reactive oxygen species, and oxidizing ability

A mononuclear peroxovanadium(V) complex with histamine-N,N-diacetate (histada), K[VO(O(2))(histada)], and a dinuclear peroxovanadium(V) complex with 2-oxo-1,3-diaminopropane-N,N,N',N'-tetraacetate (dpot), Cs(3)[(VO)(2)(O(2))(2)(dpot)], were prepared and characterized. The self-decomposition reaction was examined for these peroxovanadium(V) complexes as well as for K[VO(O(2))(cmhist)] (cmhist = N-carboxymethylhistidinate). The reaction profiles depicted by the absorbance change in the UV-vis spectrum show a sigmoid shape with an induction period. The induction period is reduced by the addition of acid, fluoride, thiocyanate, VO(2+), VO(2)(+), and trolox compared to the solution containing perchlorate. On the other hand, the induction period was elongated by the addition of chloride, bromide, and 2-tert-butyl-p-cresol. These behaviors are discussed on the basis of a radical chain mechanism. The self-decomposition reactions have also been followed by the (1)H and (51)V NMR and EPR spectra. These spectral studies as well as the UV-vis spectral study indicate that vanadium(V) is partly reduced to vanadium(IV) in the self-decomposition process. The histada complex yields a mixed-valence dinuclear complex in a concentrated solution, and the dpot complex yields a mixed-valence tetranuclear complex. The reduction of vanadium ion suggests that the peroxo ligand may act as a reducing agent. In order to know the fate of the peroxo ligand, we tried to detect superoxide anion and hydroxyl radical, which were anticipated to be produced in the self-decomposition process. The formation of superoxide anion was spectrophotometrically confirmed using two independent methods, including the reduction of cytochrome c and the reduction of sodium 4-[3-(iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate (WST-1). The formation of hydroxyl radical was confirmed by an EPR spin trapping technique. The oxidizing abilities of the peroxovanadium(V) complexes toward bovine serum albumin (BSA) were also evaluated. In the protein carbonyl assay, it was found that the total amount of protein carbonyl in BSA was increased by the reaction with the peroxovanadium complexes in the concentration-dependent manner. In addition, the oxidation of sulfhydryl group in BSA induced by the peroxovanadium complexes was confirmed.